DEVICE TO CONTROL FIELD OF DC TRACTION MOTOR Russian patent published in 2006 - IPC B60L15/04 H02P7/06 

FIELD: railway transport; vehicles with dc traction motors.

SUBSTANCE: proposed field control device of dc traction motor has supply source, series-connected armature winding and field winding, current sensors, resistors and contactors. First output of first current sensor is connected with first output of second current sensor whose output is connected with first input of comparator. First output of contactor is connected with common output of first and second resistors. Device includes also matching units. Outputs of first and second matching units are connected with inputs of first and second switch elements, respectively. Third and fourth switch elements, third and fourth matching units, first and second NAND gates, inverter, pulse shaper, trigger, pulse generator, pulse counter are introduced additionally. Second output of contactor is connected to common output of armature winding and field winding of dc motor, its control contact is connected with pulse shaper input, first input of first NAND gate and first input of second NAND gate. Output of pulse shaper is connected to first input of trigger whose output is connected to first input of pulse counter, output of pulse generator is connected to second input of pulse counter whose first, second, third and fourth outputs are connected with inputs of first, second, third and fourth matching units, respectively. Outputs of third and fourth matching units are connected with inputs of third and fourth switch elements, respectively. Fifth output of pulse counter is connected with second inputs of first NAND gate whose output is connected with second input of trigger. Output of first current sensor is connected with second input of comparator whose output is connected with input of inverter and second input of second NAND gate whose output is connected with third input of pulse counter. Output of inverter is connected with third input of trigger. Free output of armature winding of dc traction motor is connected to supply source, free output of field winding of dc traction motor is connected with second output of first current sensor. Common output of third and fourth resistors is connected to first output of contactor. Free outputs of first, second, third and fourth resistors are connected to first outputs of first, second, third and fourth switch elements, respectively, their second outputs are united and connected to second output of second current sensor, and common output of first and second current sensors is connected with ground.

EFFECT: improved reliability of operation owing to improved switching of traction motor under transient conditions.

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